Black-Hole Uncertainty Entails an Intrinsic Time Arrow. a Note on the Hawking-Penrose Controversy

Any theory that states that the basic laws of physics are time-symmetric must be strictly deterministic. Only determinism enables time reversal of entropy increase. A contradiction therefore arises between two statements of Hawking. A simulation of a system under time reversal shows how an intrinsic time arrow re-emerges, destroying the time reversal, when even slight failure of determinism occurs.Comment: 9 pages, 4 figure

Dust Emission from IRC+10216

Infrared emission from the dust shell around IRC+10216 is analysed in detail, employing a self-consistent model for radiatively driven winds around late-type stars that couples the equations of motion and radiative transfer in the dust. The resulting model provides agreement with the wealth of available data, including the spectral energy distribution in the range 0.5--1000 \mic, and visibility and array observations. Previous conclusions about two dust shells, derived from modelling the data with a few single-temperature components of different radii, are not supported by our results. The extended, continuous temperature and density distributions derived from our model obviate the need for such discrete shells. The IR properties vary with the stellar phase, reflecting changes in both the dust condensation radius $r_1$ and the overall optical depth $\tau$ -- as the luminosity increases from minimum to maximum, $r_1$ increases while $\tau$ decreases. We find that the angular size of the dust condensation zone varies from 0.3 arcsec at minimum light to 0.5 arcsec at maximum. The shortage of flux at short wavelengths encountered in previous studies is resolved by employing a grain size distribution that includes grains larger than \about\ 0.1 \mic, required also for the visibility fits. This distribution is in agreement with the one recently proposed by Jura in a study that probed the outer regions of the envelope. Since our constraints on the size distribution mostly reflect the envelope's inner regions, the agreement of these independent studies is evidence against significant changes in grain sizes through effects like sputtering or grain growth after the initial formation at the dust condensation zone.Comment: LaTeX with 3 figures, requires MNRAS mn.sty; figures and/or complete PS or PS.Z preprint (7 pages) available by anonymous ftp at ftp://asta.pa.uky.edu/ivezic/irc10216/irc10216.ps (or fig1.ps, fig2.ps, fig3.ps

Self-similarity and scaling behavior of IR emission from radiatively heated dust: I. Theory

Dust infrared emission possesses scaling properties. Overall luminosity is never an input parameter of the radiative transfer problem, spectral shape is the only relevant property of the heating radiation when the inner boundary of the dusty region is controlled by dust sublimation. Similarly, the absolute scales of densities and distances are irrelevant; the geometry enters only through angles, relative thicknesses and aspect ratios, and the actual magnitudes of densities and distances enter only through one independent parameter, the overall optical depth. Dust properties enter only through dimensionless, normalized distributions that describe the spatial variation of density and the wavelength dependence of scattering and absorption efficiencies. Scaling enables a systematic approach to modeling and classification of IR spectra. We develop a new, fully scale-free method for solving radiative transfer, present exact numerical results, and derive approximate analytical solutions for spherical geometry, covering the entire range of parameter space relevant to observations. Scaling implies tight correlations among the SEDs of various members of the same class of sources such as young stellar objects, late-type stars, etc. In particular, all members of the same class occupy common, well defined regions in color-color diagrams. The observational data corroborate the existence of these correlations.Comment: 14 pages, 10 Postscript figures (included), uses mn.sty. To appear in Monthly Notices of the Royal Astronomical Societ

Comments on (Non-)Chiral Gauge Theories and Type IIB Branes

We use type IIB brane configurations which were recently suggested by Hanany and Zaffaroni to study four dimensional N=1 supersymmetric gauge theories. We calculate the one loop beta function and realize Seiberg's duality using a particular configuration. We also comment on the anomaly cancelation condition in the case of chiral theories and the beta function in the case of chiral and SO/Sp theories.Comment: 11 pages, Latex. 5 figures. Several changes in text and a reference was added. Accepted to Phys.Lett.

On mixed phases in gauge theories

In many gauge theories at different values of parameters entering Lagrangian, the vacuum is dominated by coherent condensates of different mutually non-local fields (for instance, by condensates of electric or magnetic charges, or by various dyons). It is argued that the transition between these "dual to each other" phases proceeds through the intermediate "mixed phase", having qualitatively different features. The examples considered include: ordinary YM, N=1 SYM, N=1 SQCD, and broken N=2 SYM and SQCD.Comment: Latex, 19 pages; Talk given at "Continuous Advances in QCD-2002/Arkadyfest", honoring the 60-th birthday of Arkady Vainshtein; 17-23 May 2002, University of Minneapolis, Minnesota, USA; v.3: the extended and improved versio

Black Hole Evaporation Entails an Objective Passage of Time

Time's apparent passage has long been debated by philosophers, with no decisive argument for or against its objective existence. In this paper we show that introducing the issue of determinism gives the debate a new, empirical twist. We prove that any theory that states that the basic laws of physics are time-symmetric must be strictly deterministic. It is only determinism that enables time reversal, whether theoretical or experimental, of anyentropy-increasing process. A contradiction therefore arises between Hawking's argument that physical law is time-symmetric and his controversial claim that black-hole evaporation introduces a fundamental unpredictability into the physical world. The latter claim forcibly entails an intrinsic time-arrow independent of boundary conditions. A simulation of a simple system under time reversal shows how an intrinsic time arrow re-emerges, destroying the time reversal, when even the slightest failure of determinism occurs. This proof is then extended to the classical behavior of black holes. We conclude with pointing out the affinity between time's arrow and its apparent passage.Comment: 15 pages, 3 figure